Urinary Stem Cells and Their Therapeutic Potential


Yuanyuan Zhang, assistant professor of regenerative medicine at Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine, has extended earlier work on stem cells from urine that suggests that these cells might be more therapeutically useful than previously thought.

These urinary stem cells can be isolated from a patient’s urine sample, and they can be induced, in the laboratory, to form bladder-type cells; smooth muscle and urothelial (bladder-lining) cells. Such stem cells could certainly be used to treat urinary tract problems, even though a good deal more work is required to confirm that they can do just that.

Nevertheless, Zhang and his co-workers have discovered that these urinary tract stem cells are much more plastic than previously thought. In the laboratory, Zhang and others have managed to differentiate urinary tract stem cells into bone, cartilage, fat, skeletal muscle, nerve, and endothelial cells (the cells that line blood vessels). This suggests that urine-derived stem cells could be used in a variety of therapies.

USCs undergo multipotential differentiation in vitro. (a-c) endothelial differentiation of USCs. USCs (p3) were induced to endothelial lineage by culture in EBM-2 medium containing VEGF 50 ng/ml for 14 days. (a) In vitro vessel formation. Endothelial differentiated USCs were cultured on Matrigel for 18h to form branched networks (angiogenesis) and tubular structures. Scale bar = 100μm. (b) Expression analysis of endothelial-specific transcripts by RT-PCR. (c) Immunofluorescence staining using endothelial-specific markers revealed enhanced staining of the markers with differentiation (middle row) compared to the non-treated control (top row). Scale bar = 50μm.
USCs undergo multipotential differentiation in vitro. (a-c) endothelial differentiation of
USCs. USCs (p3) were induced to endothelial lineage by culture in EBM-2 medium containing
VEGF 50 ng/ml for 14 days. (a) In vitro vessel formation. Endothelial differentiated USCs were
cultured on Matrigel for 18h to form branched networks (angiogenesis) and tubular structures. Scale
bar = 100μm. (b) Expression analysis of endothelial-specific transcripts by RT-PCR. (c)
Immunofluorescence staining using endothelial-specific markers revealed enhanced staining of the
markers with differentiation (middle row) compared to the non-treated control (top row). Scale bar =
50μm.

Zhang said that urinary tract stem cells could be used to treat urological disorders such a kidney disease, urinary incontinence, and erectile dysfunction. However, Zhang is optimistic that they can also be used to treat a wider variety of treatment options, such as making replacement bladders, urine tubes, and other urologic organs.

Since these stem cells come from the patient’s own body, they can have a low chance of being rejected by the immune system. Also, they do not cause tumors when implanted into laboratory animals.

In their latest work, Zhang and his colleagues obtained urine samples from 17 healthy individuals whose ages ranged from five to 75 years old. Even though these stem cells are only one of a large collection of cells in urine, isolating urinary stem cells from urine only requires minimal processing.

A single USC (inset) is followed through different passages (p0-p12). The cells were expanded to a colony were cultured in KSFM-EFM medium with 5% serum and images recorded with passage. Images shown at x100
A single USC (inset)
is followed through different passages (p0-p12). The cells were expanded to a colony were cultured in
KSFM-EFM medium with 5% serum and images recorded with passage. Images shown at x100

In the laboratory, Zhang and his team differentiated the cells into derivatives of all three embryological layers (endoderm – skin and nervous tissue; mesoderm – bone, muscle, glands, and blood vessels; and endoderm – digestive system).

Differentiation of one USC clone into UCs and SMCs. (a) USCs (p3) t were used to differentiate into two distinct lineages. Culture in SMCs-lineage differentiation (2.5 ng/ml TGF-􀈕1 and 5 ng/ml PDGF-BB) and UCs-lineage differentiation (30 ng/ml EGF) medium was used for 14 days.
Differentiation of one USC clone into UCs and SMCs. (a) USCs (p3) t were used to
differentiate into two distinct lineages. Culture in SMCs-lineage differentiation (2.5 ng/ml TGF-􀈕1 and
5 ng/ml PDGF-BB) and UCs-lineage differentiation (30 ng/ml EGF) medium was used for 14 days.

After showing the multipotent nature of urinary tract stem cells in the laboratory, Zhang and others took smooth muscle cells and urothelial cells made from urinary tract stem cells and transplanted them into mice with tissue scaffolds that had been made from decellularized pig intestine. The scaffolds only had extracellular molecules and not cells. After one month, the implanted cells had formed multi-layered, tissue-like structures.

USCs were infected with BMP9 or control GFP and were injected subcutaneously into nude mice. i) Bony masses were only observed in mice implanted with BMP-transduced USCs at week 4. ii) The harvested bony masses were subjected to microCT imaging revealing the isosurface (left) and density heat maps (right).
USCs were infected with BMP9 or control GFP and were
injected subcutaneously into nude mice. i) Bony masses were only observed in mice implanted with
BMP-transduced USCs at week 4. ii) The harvested bony masses were subjected to microCT imaging
revealing the isosurface (left) and density heat maps (right).

Urinary tract stem cells or as Zhang calls them, urine-derived stem cells or USCs, have many cell surface characteristics of mesenchymal stem cells from bone marrow, but they are also like pericytes, which are cells on the outside of small blood vessels. Zhang and others suspect that USCs come from the upper urinary tract, including the kidney. Patients who have had kidney transplants from male donors have USCs with a Y chromosome in them, which suggests that the kidney is a source or one of the sources of these cells.

Determination of USC source. Several clones of USCs (p3) were cultured and analyzed for expression of kidney-lineage marker. (a) FISH (left) and amelogenin gene PCR analysis (right) analysis of USCs isolated from urine obtained from a male donor-to-female recipient kidney transplant for presence of Y-chromosome (L: DNA ladder, M: male control, F: female control, A4: USC from male donor-to-female recipient urine sample, N: negative control).
Determination of USC source. Several clones of USCs (p3) were cultured and analyzed for
expression of kidney-lineage marker. (a) FISH (left) and amelogenin gene PCR analysis (right)
analysis of USCs isolated from urine obtained from a male donor-to-female recipient kidney transplant
for presence of Y-chromosome (L: DNA ladder, M: male control, F: female control, A4: USC from
male donor-to-female recipient urine sample, N: negative control).

Even more work needs to be done before we can truly become over-the-moon excited about these cells as a source of material for regenerative medicine, Zhang’s work is certainly an encouraging start.

See Shantaram Bharadwaj, et al., Multi-Potential Differentiation of Human Urine-Derived Stem Cells: Potential for Therapeutic Applications in Urology. Stem Cells 2013 DOI: 10.1002/stem.1424.

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mburatov

Professor of Biochemistry at Spring Arbor University (SAU) in Spring Arbor, MI. Have been at SAU since 1999. Author of The Stem Cell Epistles. Before that I was a postdoctoral research fellow at the University of Pennsylvania in Philadelphia, PA (1997-1999), and Sussex University, Falmer, UK (1994-1997). I studied Cell and Developmental Biology at UC Irvine (PhD 1994), and Microbiology at UC Davis (MA 1986, BS 1984).